1. Field of the Invention
The invention relates generally to hydrocarbon and water emulsions and more particularly to a biological method for preventing rancidity, spoilage and instability of hydrocarbon and water emulsions and for increasing the lubricity of the same.
2. Description of the Related Art
Oil and water emulsions are used in many industries such as metal machining, textile, grease, metal forming, leather manufacturing, for various purposes such as cooling, lubricating, softening, corrosion protection, etc. The oil and water emulsions are an ideal place for microbial growth, which, if not prevented or controlled, causes the degradation of the emulsions, including making the emulsions useless.
In some industrial systems, such as the machines used in cutting metals, when the system shuts down and the emulsion circulation stops, the oxygen level in the emulsion declines and the resulting anaerobic environment promotes anaerobic bacterial growth and increase in H2S (hydrogen sulphide) gas which in turn causes an odor and reduction in the pH, and an eventual emulsion breakdown and separation of oil and water.
It is notable that the presence of fungi, yeast or mold, in the emulsions will result in a musty odor. Also, while, fungi usually do not affect the performance of the emulsions, in some cases a heavy fungal growth could result in blockage of parts, such as in fluid transfer pipes. In addition, the presence of fungi may have some harmful health effects on workers.
There has been considerable effort to improve emulsion formulations by making them bioresistant and by reducing the materials included in the formulations, which could be used as a food source by microbes. Some of the effort led to the use of a polymer with antimicrobial, bioresistant properties for metal working fluid and coatings. The bioresistant moiety that was linked into the backbone of the polymer is bromine/nitro group. In spite of all the effort and the solution provided (i.e., bioresistant polymer), there is still much microbial growth noticed in such fluids.
Furthermore, in many emulsions, there are ingredients such as hydrocarbons, surfactants, sulfur and phosphorous, which are suitable nutrients for microbial growth, and are thus biosupportive and not bioresistant ingredients. In some emulsions, the microbial growth could be so intense as to affect the physical and chemical properties of the emulsion, such as pH, rheological performance, emulsion stability, corrosion protection and odor, and even emulsion breakage resulting in the fluid becoming useless.
The level of destruction caused by the microorganisms depends on such factors as their type, population, the physical state of the system such as temperature, cleanliness, type of water used, and the age of the emulsion.
Other efforts led to the proposal of methods for preventing microbial contamination and degradation of emulsions, or other fluids containing biosupportive ingredients, by using biocides. For this purpose, a range of various chemical compounds are produced and used. Some of these biocides are compounds containing chemical entities such as halogens, organometallics, quaternary ammonium, phenols, metal salts, polycyclic amines, formaldehyde, and sulfur. Biocide performance is calculated in different manners, which include considering their effective concentration range (the optimum concentration for controlling the microbial growth) and their power of microorganism destruction which will determine the effectiveness of the remaining biocide in the environment. Other considerations are biocide's stability, physical properties, toxicity level, economics and environmental aspects.
Many biocides used in the industry at the present are either bactericide, fungicide or both and they can eliminate most and sometimes all of the microorganisms present in the targeted environment. These biocides could be part of the original formulation or could be added to the system continuously or periodically as needed.
A drawback of using biocide as a method for controlling microorganism growth in emulsions is the fact that microbes are present in most environments, such as air, water, soil and operators' hands and they continually contaminate the systems where the emulsions are used, and thus, the emulsions themselves. This causes the reduction and/or the elimination of the biocides in the respective emulsions, which, thus, require continual and/or periodical additions of biocides. Other drawbacks of biocides use are their adverse effects on the environment and workers' health. Another drawback is that microbes become resistant to the used biocide and thus the biocide has to be changed periodically.
It should also be noted that not all the microorganisms and in particular not all the bacteria in the nature are harmful towards emulsions and some of them would not change the chemical and the physical properties of such fluids. Contrarily, some of these bacteria promote the stability of the emulsion by secreting biosurfactant which helps in stabilizing the emulsion and some might have biocidal properties. Thus, killing all microorganisms by using biocides may be counterproductive.
Thus, as there is always a high potential for the hydrocarbon and water emulsions to be attacked by microorganisms, to make them spoiled and useless, there is a great need for a new and improved method that is effective and economical in protecting them from such attacks, and that addresses and solves the problems with the prior art described above.
The aspects or the problems and the associated solutions presented in this section could be or could have been pursued; they are not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches presented in this section qualify as prior art merely by virtue of their presence in this section of the application.